My lunch buddy isn't here today. At first I was worried, maybe he's sick or been in a car accident? Then I realized that it's Yom Kippur, the most sacred of the Jewish holidays.
This is the Day of Atonement, for Jews. It's a day characterized by fasting, prayer, and seeking forgiveness. This is the one day of the year when attending synagogue is practically mandatory—even for secular Jews.
Who are "secular" Jews, you might ask? They're people who belong to the culture of Judaism but who don't believe in God. That can be a substantial percentage of Jews in some countries. Even in Israel, about 30% of the citizens are atheists (adherents.com).
I'm pretty sure this phenomenon (secular "religion") is quite common. I know lots of secular Roman Catholics and secular Anglicans.
Happy Yom Kippur1 to all Jews, secular and otherwise.
1. It seems a bit strange to be wishing happy Yom Kippur on a day devoted to atonement but I'm told this is appropriate for an atheist or other goya.